Ezekiel 33:1-3

1The Lord gave this message to me:

2‘Son of man, speak to your people. Say to them, “Think about what might happen if I send an army to attack a country. The people of that country might choose one of their own men to be a guard to warn them about danger.

3Then, if the guard sees that enemy soldiers are ready to attack, he must blow a trumpet to warn his people.